<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>flex-basis100%</title>
</head>
<style>
  body {
    background-color: black;
  }
  .box{
    width: 100px;
    height: 100px;
    background-color: #fff;
    display: flex;
    flex-wrap: wrap;
    justify-content: flex-end; 
    align-content: space-between;
  }
  .column {
    /* flex-basis属性定义了在分配多余空间之前，项目占据的主轴空间（main size）。浏览器根据这个属性，计算主轴是否有多余空间 */
    /* 100% 说明主轴没有空间需要换行 */
    flex-basis: 100%;  
    /* display: flex;
    justify-content: space-between; */
  }
  .item {
    width: 20px;
    height: 20px;
    background-color: black;
    border-radius: 50%;
  }
  /* .item:nth-child(2) {
    align-self: flex-end;
  }
  .item:nth-child(3) {
    align-self: flex-end;
  } */
</style>
<body>
  <div class="box">
    <div class="column">
      <span class="item">11</span>
      <span class="item">22</span>
    </div>
    <div class="column">
      <span class="item">22</span>
      <span class="item">11</span>
    </div>
  </div>
 
</body>

<script>

</script>
</html>